i have a couple ideas of what could be the problem but i wanted input from the board.
I bought my 93 wrecked and since then had the front end pulled over a inch.
the metal arm that goes from the rear end to the transmission is bent.it is almost touching the driveshaft. I have not yet replaced. the car has been driving fine under normal conditions<<<<<doing the speed limit. well on day i hit the highway and wanted to see how fast i could actually hit 150+ in the camaro....i had one scary ride coming. as i hit 90mph the car started to slightly fishtail. i backed off immeditaly. i went for it again and done the same thing. ...a few weeks past. I am now starting to notice my car shimmy doing normal driving. 30-50 mph stop and go traffic. this is starting to concern me and my parents. what do you'all think?

 

Any suspension items that are bent need to be replaced. By your description, the metal arm is the torque arm. Pick one up at a junkyard or replace it with an aftermarket one if you have the money. Chances are, the transmission mount where the front of the torque arm attaches is also bent.

I also suggest you get a four wheel alignment after replacing the torque arm. That will tell you quite a bit about what's going on.